This invention relates to electric lamps in general and, in particular, to a supplemental high mounted stop lamp for motor vehicles. More specifically, the invention deals with such a lamp featuring improved means for mounting the lamp to a windowpane, typically the rear windowpane of a motor vehicle, against the likelihood of accidental detachment therefrom in the face of the thermal expansion or contraction of the lamp body and the windowpane at different rates.
The high mounted stop lamp is finding ever increasing use on motor vehicles, passenger cars in particular, to supplement the stop lamp system and to provide a signal through intervening vehicles to operators of following vehicles. Some supplemental stop lamps are mounted high on the interior surface of the rear windowpane. Typically, such a lamp comprises a row of light emitting diodes mounted to a printed circuit board and electrically connected to the conductive pattern thereon. The light emittering diodes together with the printed circit board is housed in a horizontally elongated, boxlike lamp body with an open side which is closed by a lens or lenses and which is contoured to fit the inside curvature of the rear windowpane.
Conventionally, this type of supplemental stop lamp was mounted by bonding the open side of the lamp body directly to the rear windowpane. This practice is objectionable because the lamp body, which typically is of a plastic, and the windowpane, being of glass, have different rates of thermal expansion. The lamp body was easy to detach from the windowpane as it repeatedly underwent thermal expansion and contraction at a rate different from that of the windowpane with changes in temperature over the years. The lamp body was even more susceptible to detachment because of its elongate shape, which shape made it far more liable to expand or contract in its longitudinal direction than in its transverse direction.